tools: bpftool: add an option to prevent auto-mount of bpffs, tracefs

In order to make life easier for users, bpftool automatically attempts
to mount the BPF virtual file system, if it is not mounted already,
before trying to pin objects in it. Similarly, it attempts to mount
tracefs if necessary before trying to dump the trace pipe to the
console.

While mounting file systems on-the-fly can improve user experience, some
administrators might prefer to avoid that. Let's add an option to block
these mount attempts. Note that it does not prevent automatic mounting
of tracefs by debugfs for the "bpftool prog tracelog" command.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 9e4499c926fa..052c91d4dc55 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -44,7 +44,8 @@
 #define HELP_SPEC_PROGRAM						\
 	"PROG := { id PROG_ID | pinned FILE | tag PROG_TAG }"
 #define HELP_SPEC_OPTIONS						\
-	"OPTIONS := { {-j|--json} [{-p|--pretty}] | {-f|--bpffs} | {-m|--mapcompat}"
+	"OPTIONS := { {-j|--json} [{-p|--pretty}] | {-f|--bpffs} |\n"	\
+	"\t            {-m|--mapcompat} | {-n|--nomount} }"
 #define HELP_SPEC_MAP							\
 	"MAP := { id MAP_ID | pinned FILE }"
 
@@ -85,6 +86,7 @@ extern const char *bin_name;
 extern json_writer_t *json_wtr;
 extern bool json_output;
 extern bool show_pinned;
+extern bool block_mount;
 extern int bpf_flags;
 extern struct pinned_obj_table prog_table;
 extern struct pinned_obj_table map_table;